The use of optical fibers in communication systems is growing at an unprecedented rate. Low loss optical fibers which are produced by any of several techniques may be stranded into cables, or enclosed individually in a jacket and used in the transmission of large amounts of information which is typically binary (i.e., on/off pulses). An optical fiber comprises a thin glass fiber which has been processed to confine light along its longitudinal axis, and then enclosed within one or more layers of a protective coating material that cushions the glass fiber against severe bending and protects it from contaminants such as water vapor to preserve its inherently high tensile strength. In some applications, no additional jacketing is applied to the individual fibers; however, in other applications is it necessary to add a buffer material around each coated fiber. In these situations, a layer of nylon or polyvinylchloride, for example, is extruded around the individual optical fibers to form what is known as a "buffered optical fiber." In most interconnection cable applications, one or more of these buffered fibers is combined with strength members of various types and covered with a polymer jacket or sheath.
In optical fiber connectors, particularly duplex connectors which are used for making connections to a pair of optical fibers, it is necessary to provide a force transfer system at the cable-entrance end of the connector to hold strength members of the cable in such a manner that tensile forces on the cable are transferred to the housing of the connector. These tensile forces are also coupled to the optical fiber(s) which reside in the cable and, without proper restraint, will pull the fibers from the connector back into the cable. Such shortening of the fibers inside the connector case can cause high-stress bending where the fiber is joined to a plug assembly thereby causing a decrease in long-term reliability.
A known technique for immobilizing buffered fibers within a duplex optical fiber connector utilizes a cylindrical rubber grommet which is secured within the connector housing. Epoxy is applied to prevent the grommet itself from moving due to exposure to high/low temperature extremes. The grommet includes three openings that are arrayed in a triangular pattern and extend between opposite ends of the grommet along a direction that is parallel to its central axis. Two of the openings are grooved to facilitate gripping the buffered fiber. The remaining opening is smooth and receives a metal pin which, when inserted, causes the grooved openings to compress around the buffered fibers to hold them securely. And while this technique is useful for immobilizing buffered fibers within an optical fiber connector, it is somewhat expensive, it requires careful manual assembly, and adhesive materials must be handled and cured.
What is needed, and what is not supplied by the prior art, is a force transfer system for use within a connector that grips one or more optical fibers in a manner which is cost effective, easy to assemble, and preferably avoids the use of adhesives.